Assessment of potential environmental risks of transgene flow in smallholder farming systems in Asia: Brassica napus as a case study in Korea

摘要

The cultivation of genetically modified (GM) crops has raised many questions regarding their environmental risks, particularly about their ecological impact on non-target organisms, such as their closely-related relative species. Although evaluations of transgene flow from GM crops to their conventional crops has been conducted under large-scale farming system worldwide, in particular in North America and Australia, few studies have been conducted under smallholder farming systems in Asia with diverse crops in co-existence. A two-year field study was conducted to assess the potential environmental risks of gene flow from glufosinate-ammonium resistant (GR)Brassica napusto its conventional relatives,B. napus,B. juncea, andRaphanus sativusunder simulated smallholder field conditions in Korea. Herbicide resistance and simple sequence repeat (SSR) markers were used to identify the hybrids. Hybridization frequency ofB. napus × GRB. napuswas 2.33% at a 2 m distance, which decreased to 0.007% at 75 m. ForB. juncea, it was 0.076% at 2 m and decreased to 0.025% at 16 m. No gene flow was observed toR. sativus. The log-logistic model described hybridization frequency with increasing distance from GRB. napustoB. napusandB. junceaand predicted that the effective isolation distances for 0.01% gene flow from GRB. napustoB. napusandB. junceawere 122.5 and 23.7 m, respectively. Results suggest that long-distance gene flow from GRB. napustoB. napusandB. junceais unlikely, but gene flow can potentially occur between adjacent fields where the smallholder farming systems exist.